1. Field of the Invention
The present invention relates to a trim and tilt apparatus for a marine vessel propulsion machine and a marine vessel propulsion machine.
2. Description of Related Art
In the related art, an apparatus which can absorb an excessive impulsive force even when an impulsive force caused by an impact of underwater obstacles with respect to a marine vessel propulsion machine becomes excessive is suggested.
For example, a trim and tilt apparatus described in JP-A-2012-86666 includes: a housing in which a cylinder device is used while linked to one of a ship body and a marine vessel propulsion machine, and forms a trim chamber having a large diameter; a cylinder which is telescopically inserted into the trim chamber of the housing, and forms a tilt chamber having a small diameter; a trim piston having a large diameter which is fixed to an end portion of the cylinder in the trim chamber of the housing, and divides the trim chamber into a first trim chamber which is on a cylinder accommodating side, and a second trim chamber which is on a cylinder non-accommodating side; a piston rod which is used while linked to the other one of the ship body and the marine vessel propulsion machine, and is telescopically inserted into the tilt chamber of the cylinder; a tilt piston having a small diameter which is fixed to an end portion of the piston rod in the tilt chamber of the cylinder, and divides the tilt chamber into a first tilt chamber which is on a piston rod accommodating side, and a second tilt chamber which is on a piston rod non-accommodating side; and a free piston which is disposed in the cylinder nipped by the trim piston and the tilt piston, and divides the chamber into the second trim chamber and the second tilt chamber. In addition, in the trim and tilt apparatus, a communication path which allows the first trim chamber and the first tilt chamber to communicate with each other is provided in the cylinder, a shock relief valve which moves working oil of the first trim chamber and the first tilt chamber to the second tilt chamber at a set pressure, and a return valve which returns the working oil of the second tilt chamber to the first tilt chamber, are provided in the tilt piston, and an oil path which guides an inlet that is provided in the tilt piston and communicates with the first tilt chamber of the shock relief valve to the communication path that communicates with the first trim chamber at an extending end of the piston rod, is provided in the tilt piston.
In addition, in a tilt and trim apparatus described in JP-A-2000-72088, a first shock relief valve which releases an oil pressure on a tilt cylinder side to the second oil chamber side when a force in the extending direction which is equal to or greater than a predetermined value acts, is provided in the tilt piston, a liner member which is oil-tightly and slidingly in contact with an inner circumferential surface of the trim cylinder is provided on an outer circumferential surface of an upper end of the tilt cylinder, and a second shock relief valve which releases an oil pressure on a first oil chamber side to the second oil chamber side when a force in the extending direction which is equal to or greater than a predetermined value acts, is provided in the liner member.